C5 Corvette Seat Module Repair - All Cracked Up

Repairing C5 Cold-Solder Joints

When it comes to electrical bugs in your Corvette's wiring system, the thought of having to follow a wiring diagram or purchase an expensive component is enough to make even the bravest amateur mechanic's skin crawl. In this article, we'll show you an easy, no-cost way to repair many such maladies.

Intermittent problems with electronic modules or circuit boards are often the result of a cold-solder joint. Cold-solder joints are quite common in remote-keyless-entry fobs, electronic climate-control units, ABS/traction-control modules, digital dashes, and the part we'll be repairing today-the seat-control module.

The term "cold-solder joint" refers to a solder connection that wasn't heated enough during manufacturing, was cooled too quickly, or had its component pins moved before the solder had a chance to solidify. With time, cold-solder joints can become problematic due to vibration, repeated thermal cycling, or constant exposure to high temperatures.

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We found that hitting the top of the cushion allowed our C5's seat to temporarily operate. This was a good indication that the problem lay in one or more of the connections in the seat module.

When diagnosing a bad solder joint, try tapping on the suspect component. If this causes it to work temporarily, you'll have a pretty good indication that you've found the problem. For example, when trying to determine why one of the seats in our C5 wouldn't move forward and back, we found that hitting the top of the cushion briefly rectified the glitch. This led us to deduce that the seat module located under the cushion was the culprit.

You can repair cold-solder joints without knowing anything about circuitry. Use a light and a magnifying glass to examine components for hairline cracks in the solder around the pins. Fixing them will require a low-wattage, pencil-style soldering iron and some rosin-core solder, which can be found at any Radio Shack or auto-parts store.

Apply a small amount of solder to the heated iron, then use the tip of the iron to heat the joint and apply the solder at the same time. The solder should flow evenly on the joint, repairing the connection. This process should only take a second or two. Any more, and the heat from the iron could damage the circuit board or the component itself. Repeat as needed, soldering any and all questionable connections.

Repairing cold-solder joints can fix many of your Corvette's intermittent electrical problems, so don't be afraid to try this simple repair. Remember, the components in question are already broken and would normally be discarded. You have nothing to lose by trying.

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We found that hitting the top of the cushion allowed our C5's seat to temporarily operate. This was a good indication that the problem lay in one or more of the connections in the seat module.

To access the module, the seat must be removed. The first step is to remove the escutcheons covering the front-seat hold-down bolts, which are held in with plastic pushpins.

There are four bolts holding the seat in place; two in front and two in the rear. Loosen and remove these, but don't remove the seat itself.

Before removing the seat, you'll need to unplug the seat wiring harness. It's located on the outboard side of the seat and held in place with a clip.

Now you're ready to remove the seat and place it on a clean workspace.

When you turn the seat on its side, you'll find that the module is located under the cushion and above the seat motor.

The module is simply held in place by the seat springs. You'll need to work the module out gently so you won't damage the springs.

Once you have the module out, you can unplug its wiring harness. Be careful not to damage the locking tabs. At this point you can either replace the module (at a cost of $399.90) or try repairing it yourself.

The seat module housing simply snaps together. Gently pry it open with the tip of a screwdriver.

With the seat module open, you can begin your inspection. The resistors are the large brown cylinders with the orange, yellow, brown, and silver paint rings around them. Look for any discoloration of the circuit board around these resistors. This occurs because of the large amount of energy these resistors dissipate.

Now look for cold-solder joints. These appear as a dull gray color and sometimes look like a drop of water, whereas good solder joints appear both concave and shiny. Sometimes you can actually see a crack around the base of the pin.

Heat the solder pencil and melt a little solder on the tip. Then touch the tip to each defective joint and hold it there as you apply the solder; the bead should flow evenly. Remove the tip and let it cool off. (Don't flood the area with so much solder that it spreads across to another joint; these joints shouldn't touch each other.) This process will reconnect any cracked or damaged joints. Remember: When in doubt, solder any suspect connections. You're now ready to reinstall your seat and go cruising.

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